I would try the Nismo headers with hi flow cats...
I'll have to let you know. I made 391 hp and 410tq with stock headers and cats. A/F ratio was 12.5. I am running dangerously lean now, so I will have to get that straighten out before I can answer your question.chargedTitan said:Kuntao and Qship- Did you guys experience performance gains with the longtubes? I expected some loss of torque at the low end, and more H.P.at the top. But what I got was a huge loss of torque and horsepower throughout the powerband. I wonder if my cat back system is to blame. With the stock manifolds and cats, it's a freakin' rocket.